Enhancing second harmonic generation efficiency by coupling fano and surface lattice resonances in dolmen-type gold metasurface

Optical metasurfaces, planar nanostructures comprised of subwavelength meta-atoms, have garnered significant attention for their remarkable ability to finely manipulate optical properties at the nanoscale. In this study, we present a dolmen-type gold metasurface featuring dual resonances designed to enhance second harmonic generation (SHG). Employing nonlinear scattering theory, our investigation explores the intricate interplay between Fano and surface lattice resonances (SLR), resulting in an extraordinary over 90-fold enhancement in SHG compared to single resonance scenarios. Our study paves the way for advancements on enhancing SHG of metallic metasurfaces, expanding their applications across various domains, including nonlinear optics, integrated optics, and neuromorphic photonics.